Apple may use bayonet mounts for interchangeable iPhone camera lenses

Apple is investigating the use of bayonet lens mounts —one of the most common lens attachment mechanisms used in modern photography —in its iOS device lineup, suggesting the company is mulling interchangeable lens accessories for its iOS device lineup.

An Apple patent issued by the U.S. Patent and Trademark Office on Tuesday describes a mechanism by which an iOS device, such as an iPhone or iPod, may be fitted with a bayonet mount onto which various lens types can be fastened.

As noted in Apple's U.S. Patent No. 8,687,299 for "Bayonet attachment mechanisms," the bayonet mount is both utile and aesthetically pleasing, two attributes paramount in any Apple product design. The mount correctly aligns and securely attaches lenses to a device body while keeping a relatively inconspicuous profile when not in use.

Source: USPTO

Apple notes that other mount types, such as cases with built-in screw mounts, alter the overall design of a device and are therefore undesirable from a consumer's perspective. Magnetic mounts can be disguised, but the method is not as secure as a physical interlock and may result in misaligned lenses.

Instead, Apple proposes a bayonet-style solution integrated with a device's rear-facing camera bezel. As seen above, the iPhone-side bayonets are substantially hidden within the camera surround, which would protrude slightly above the rear case. A lens element with interleaving bayonets can be aligned via a guide dot and rotated until a secure interference hold is achieved.

Detents and inserts are disposed within the bayonet mechanism to provide an increasingly tight torque lock when rotating in a certain direction. Detents on the first attachment mechanism (located on the device) force a second attachment mechanism (located on the lens) outward radially against a compliance member. As the second attachment plates are pushed outward, gaps form between the bayonets until the detents reach a secure configuration, at which point the plates move inward into a locked position.

Once the detents on both mechanisms are engaged, stop members halt further rotation, denoting a secure fit and preventing mechanical damage.

Due to a bayonet mount's snug fit, it might pose a risk to both device and lens if dropped from height. To prevent breakage from the transfer of force associated with a drop, the bayonet mechanism may incorporate a ramped surface that enables a lens to decouple from a device without rotating. The torque at which this decoupling occurs can be modified depending on the ramp angle and materials used.

Illustration showing decoupling of lens from device when dropped.

Apple has filed similar patents in the past, including recent properties for interchangeable lenses, though Tuesday's invention is perhaps closest to something the company would potentially release. While mere conjecture, it is theoretically possible that a bayonet style mount could be added to the handset without significant cost to aesthetics.

A report in March suggested the upcoming iPhone 6 design featured a protruding rear camera much like the fifth-generation iPod nano, while a dubious rumor suggested Apple is working on an interchangeable lens system for its mobile device lineup. All current iPhone models sport a camera flush with the back case.

Apple's bayonet mount patent was first filed for in 2012 and credits Emery A. Sanford and Dominic C. Toselli as its inventors.